Investigation of the Upper Critical Magnetic Field and Activation Energy in MgB2 Thin Film

Koparan E. T. , Surdu A., Sidorenko A., Yanmaz E.

JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, vol.25, no.7, pp.2235-2238, 2012 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 25 Issue: 7
  • Publication Date: 2012
  • Doi Number: 10.1007/s10948-012-1605-2
  • Page Numbers: pp.2235-2238


MgB2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a "two-step" synthesis technique. First, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 A degrees C in magnesium vapor. The upper critical field H (c2) has been estimated from temperature dependences of resistivity curves in both directions of the magnetic fields perpendicular and parallel to the c-axis. Resistivity measurements of the film were performed using a standard four-probe method under different magnetic fields up to 70 kOe in zero fields cooling regime. The upper critical magnetic field H (c2)(0) at T=0 K for 90 % of R (n) was calculated by the extrapolation H (c2)(T) to the temperature T=0 K. The results showed that H (c2)ayenab(0) and H (c2)ayenc(0) was found to be around 22 T and 18 T, respectively. Using extracted data, the zero-temperature coherence lengths and field anisotropy ratio were calculated. In order to determine the activation energy of thermally activated flux flow of the film, Arrhenius law was taken into account.